The present invention relates to continuous casting of finished products, for example, bronze castings, and more specifically to novel method and apparatus for cooling the product and the casting apparatus. The present invention is particularly suited to continuous, vertical, casting wherein the molten metal is fully solidified within the forming die, that is, prior to removal from the die.
In continuous casting of metals such as brass and the like, it is common to permit molten metal to flow from a crucible through a die which is surrounded by a cooling apparatus so that the molten metal progressively solidifies during a dwell period after which it is withdrawn by suitable apparatus. A major consideration in the efficiency of such a device is the ability to remove heat from the die.
In my U.S. Pat. No. 4,000,773, apparatus for cooling the die is shown which utilizes a cooling sleeve having intimate contact with the exterior surface of the die, which cooling sleeve is externally cooled by flowing coolant about the periphery thereof. Inasmuch as the coolant that first contacts the cooling sleeve is cold and progressively increases in temperature, there is a tendency for the cooling sleeve to be cooled unevenly and expand out of intimate contact with the die. Additionally, the incoming coolant does not uniformly contact the entire outer surface of the sleeve and the inner surface of the jacket but rather flows along a diagonal direction from the coolant inlet to the coolant outlet whereby uneven cooling of the product, die and cooling apparatus further results. Uneven cooling causes grain and strength imperfections in the cast product, while also leading to premature rupture of the forming dies and damage to the cooling apparatus. Additionally, uneven cooling often adversely affects the dimensions of the product, particularly tubular products and the diametrical dimensions of the internal passage thereof. Because of the flow path of the coolant as noted above, solidification of the molten metal within the die does not occur in the same predetermined horizontal plane which, under ideal cooling conditions, determines the diameter of the casting including the internal diameter of a tubular casting.
One of the objects of the present invention is to provide novel methods and apparatus for improving the quality of a continuously cast finished product to give it uniform strength and grain characteristics as well as accurate dimensioning.
Another object is to provide novel methods and apparatus for increasing the rate of production of continuous casting operations wherein molten metal is introduced into a forming die, fully solidified in the die and then removed from the die as a solidified finished casting and wherein the aforementioned steps are continuously repeated. Included herein are such methods and apparatus that will significantly increase the rate of production in commercial casting operations without sacrificing the quality of the cast product.
A further object of the present invention is to provide novel methods and apparatus for distributing and controlling the flow of coolant in continuous casting apparatus to enable increased and uniform heat extraction from the casting being formed and its associated forming die to thereby improve the strength and grain structure of the product while prolonging the useful life of the die and associated cooling apparatus. Included herein are such methods and apparatus which will permit the molten metal to uniformly solidify within the forming die in substantially the same plane which extends generally perpendicular to the direction of metal flow through the die and which, in vertical casting operations, extends horizontally. Further included herein are such methods and apparatus which also enable cylindrical products to be cast with precise diameters including internal diameters in the case of tubular products.
A further object of the present invention is to provide novel and improved cooling apparatus for continuous casting operations of the type described above and which may be used to achieve the above objects. Included herein is a novel cooling sleeve received within a cooling jacket and while intimately receiving the forming die and having a novel external rib configuration for controlling the flow of coolant and heat transfer particularly at the "freezing" zone of the molten metal, that is, the area at which the molten metal solidifies in the die. Included herein is such a novel cooling sleeve that will also distribute coolant to uniformly extract heat from all portions of the forming die to prolong the life of the die as well as the cooling sleeve and the surrounding cooling jacket.